Method of finishing plastic filaments, and products made therefrom



Aug. 26, 1947. H, WANDEL ET AL 2,426,328

METHOD OF FINISHING PLASTIC FILAMENTS AND PRODUCTS MADE THEREFROM Filed June 5. 1943 k U GU .6. %Z %a & ,6

5 vg mg 2!? I 7 a 2% 1' 7 a? 32 @5 f ff Patented Aug. 26, 1947 METHGD OF FINISHING PLASTIC FILA- MENTS, AND mop FROM UCTS MADE THERE- George H. Wandel, Riverside, and Theodore H. M Rider, Hinsdale, Ill., assignors, by mesne assignments, to Lever Brothers Company, Cambridge, Mass., a corporation of Maine Application June 5, 1943, Serial No. 489,780

9 Claims. (cram- 21) This invention relates to a method of finishin g plastic filaments,.and products madenthjerefrom, and particularly to such filamentswhen used in brushes. vWhile it applies-generally to many kinds of brushes for different uses-it is particularly adapted to tooth brushes. We,-,how.- ever, w1 sh it understood that the invention. is. not limited to tooth brushes even though' fort illustrative purposes we have shown and described it largely'in connection therewith. 1

One of the important problemsin connection with the manufacture of brushes is th shetmg of the ends of the bristles t me: thele ridsb the tufts of bristles so that they willbeeflicient in operation, economical in manufacture and may be quickly and easily formed with the most advantageous shapes. 1

In the present invention we have discovered I While not wishing to limit ourselves thereto,

' one-manner of applying heat to the ends of the 'bristles' for shaping .themis to provide a plate or plates of the desired shape, heat these plates to'the desiredtemperature, and bring the free ends of the bristles into contact with the heated 7 plate having the desired shape, and melt the ing the heat, the ball of material and the bristle,

" itself :remain of the original color.

group of bristle ends in close proximity to each that the most effective manner or shaping and finishing the ends of the bristles and of the bristle tufts is by applying suflicient heatftoj the ends of the bristles to cause themito melt and. 'at the same time toassurne the general contour desired for the active face of the brush. In'

making our, brushes we use synthetic bristles which may be purchased on the market under the general name of nylon bristles- -While;yior descriptive purposes; we refer to nylonfbristles, we wish it understood that we may use any synthetic bristles that are adapted to have their ends'melted by heat in accordance with the spirit I of the present invention, as for example bristles made of plastic belonging to'the group of thermoplastics.

It has been known in the manufacture of brushes, particularly tooth brushes, to insert. into handles multiple tufts of bristles, the length of which are uniformly longer than desired in the finished brush, and then to trim the surface to bristle ends to the desired outline. When a free end of a bristle more or less segregated from the adjacentbristle ends, contacts the heated plate, or other means for applying heat, and becomes melted at its end, the melted material withdraws into a ball remaining afilxed to the .bristle stalk. Under suitable conditions of temperature and nature of contact surfaces apply- When a other are contacted with the heat and the ends melted, said ends coalesce and become united together.

Whether the bristle ends individually have a ball formed thereon, or a group of said ends are coalesced together after being melted, it

is necessary to remove such balls or coalesced portions which i preierably done by combing, picking, brushing or'the like. We have found a very satisfactory way to remove said balls and coalesced portions to be to comb the bristles with a steel brush. The removal of these balls or coalesced portions leaves the free ends of the bristles in a very highly desirable condition for brushing, either as/a. tooth brush, or general purpose brush, the shape of which bristle free ends is largely controlled by the manner of applying the same against the heated plate or other heating medium. For example, when the heating medium is a flat plate the ends of the bristles may be given an angular slant by applying the end against the heated plate at an angle, more or less fiat by a corresponding application against the flat plate; curved by using a curved plate, or variously contoured by using a correspondingly contoured plate.

Among the objects of our invention are to overcome the disadvantages, and make possible the advantages, referred to above.

Other objects, advantages and capabilities will later more fully appear.

While We have shown and described preferred features of our invention we wish it understood 1 that the same are susceptible of modification and have made possible a practical method of achievchange without departing from the spirit of our invention:

In the drawings:

Fig. l is a diagrammatic fragmentary side elevation of a tooth brush embodying our invention.

Fig. 2 is an enlarged fragmentary portion of a brush body showing in end elevation a plurality of bristle tufts embodying our invention;

Fig. 3 is a side elevation of a single bristle showing the ball formed on the end thereof as the result of applying heat to the end of the bristle sufficient to melt it.

Fig. 4 is a view similar to Fig. 3 but showing the same bristle after the ball has been removed.

Fig. 5 is a side elevation of a plurality of bristles in close proximity to each other, showing how the material of the ends of the bristles coalesces together after being heated to the melting point.

Fig. 6 is a fragmentary side elevation of an end portion of a bristle that has had its end applied to a more or less flat heated plate at an angle, the bristle end being heated to the melting point, and the ball, or melted material, on the end of the bristle removed.

Fig. 7 is a view similar to Fig. 6 but showing a slightly different shape of bristle end.

Fig. 8 is .a view similar to Fig. 7 but showing a still different shape of bristle end.

Fig. 9 is a fragmentary longitudinal section of a bristle having cups, depressions or irregularities in the end surface.

Fig. 10 is a plan view of Fig. 9.

' Fig. 11 is a side elevation of a plate having a flat surface that can be heated to a temperature capable of melting the bristle end when contacting the plate.

Fig. 12 is a side elevation of a further shape of plate, showing diagrammatically a brush which has been contacted with the heated plate to give the bristle ends a general contour similar to that of the face of the plate.

Fig. 13 is a side elevation of a plate having a groove extending longitudinally along the active face of the plate. 7

Fig. 14 is an end view of the plate of Fig. 13 and showing slightly spaced thereabove diagrammatically a portion of a brush, the ends of the bristles of which have been contacted with the end was presented to the face of the plate or other means for applying heat to the bristle end. One shape for such bristle end is shown at 8 in Fig. 4. I

The fact that a clean and smooth surface fracture results when the melted portion is pulled away from the stalk is believed to be because of a definite difference in chemical structure between the melted material and the unmelted remainder of the stalk, as for example, in the case of nylon, the strands are so manufactured that there is a definite crystal orientation. When the end of the stalk is melted the melted portion loses this typical orientation. There is therefore a distinct plane of division between the oriented stalk and the disoriented melted portion, and this serves as a plane of cleavage when the melted material is broken off.

When a group of bristles in more or less close proximity to each other have their ends applied to heat sufficiently to melt them, such melted ends after solidifying will be coalesced together as shown at l in Fig. 5. When these coalesced portions are pulled off by any suitable mechanical means such as mentioned above in connection with Fig. 3, an end will be formed on each bristle of any one of many shapes depending upon the particular angle or position the bristle end was presented to the plate face or other heating means. Some of these general shapes are shown in Figs. 4 to 9 inclusive. Also other shapes of bristle ends may result, some of which are seen in Fig. 2. Regardless of the particular shape of the bristle end, they will always be of a shape to effectively hold and apply tooth paste or other material that may be used on the brush bristles.

While our invention is not limited to tooth brushes, we have shown it as so applied in Fig. 1 in which the general contour of the free ends of o the bristle tufts may be shaped by contact with a in holes in the brush body. The free ends of .the bristles are, if desired, then roughly given the general desired contour by scissor or knife trimming or by any other suitable rough trimming method desired. While nylon bristles are preferred we wish it understood that our invention is not limited thereto, but any suitable synthetic plastic bristles made of a material belonging to the group of thermoplastics may be used as desired.

As shown in Fig. 3 when a single bristle, I, of synthetic thermoplastic material is heated to the melting point and then permitted to solidify, a ball, 2, is formed on the end of the bristle. When this ball is pulled off by any mechanical means such as combing, picking, brushing or the like, the end of the bristle immediately under the ball will assume any one of a variety of shapes depending upon what angle or position the bristle heated plate of the desired shape as later more fully described. The arrangement of bristles in Fig. 2 may be applied to a tooth brush or a general purpose brush as desired.

An important feature of our invention i the shaping of the ends of brush bristles by applying them to plates having faces of the desired shape and heated to a temperature sufficiently high to melt the ends of the bristles when touched to the plate face so that the ends of the bristles will be thus brought to the general contour desired and as defined by the heated plate face. A simple form of such plate is shown in Fig. 11 as having a body portion 5 and a. flat top face 6. This plate will be preferably made of metal and will be heated. to a temperature suiiiciently high to quickly cause a melting of the material of the ends of the bristles when they are touched to the face of the plate. Such plates may be heated to the desired temperatures in any desired manner such as by the flame jets 1 fed from fuel of any desired and suitable kind supplied from any suitable source to the hollow head 8 and having openings leading to the flame jets. Many other means of heating such plates may be utilized without departing from the spirit of our invention.

In Fig. 12 we have shown a plate having a face I is required.

having a longitudinal groove 12, along the working face to give a contourto'the ends of the bristles as shown diagrammatically in the brus I! just above the plate Ii in Fig. 14. I

Figs. 15 and 16 show a plate 14 having sawtooth ridges It extending transverselycacross'the active face ofthe plate. As will be understood many different shapes of plates may be used thus giving a corresponding number of shapes available for the brush contours. a The plate in use must behot enough to melt the bristle ends. From 200 to 220 C. is a typical melting point for nylon, but the temperature of the plate could be higher than the melting point of the bristle, and preferablywill be to give a quicker melt when the bristles are in contact with the plate.

Commercially, in order to speed production, it is desirable to remove the balls 2 or the coalesced portions 4, immediately after the material-of the ball or coalesced portions has sufiiciently cooled to solidify the same. b

As will be understood all that is necessary is to touch the bristleend of the brush against the face of the heated plate until the bristle ends are melted to bring them to theshapeof the plate. -A mere contact of the bristle ends against the plate will be sufficient for this. No great pressure As stated above various -sired, whereupon each bristle can be. further-5' shortened byth'e' heattreatment desscribed herein, thereby producing the finished contour in which each bristle has been given thesmooth end typifying the invention. v

6. Also by achieving the finished trim described earlierherein, by the use of plates which instead 01 having polished surfaces, have stippled or otherwise minutely and intentionally irregular surfaces. Each bristletip can be given a surface other than plane or rounded, as for example one in which each bristle tip would have one or more minute smooth edged cups as seen in Figs. 9 and 10, which will aid in holding particles ,of dentriflce and thus increase the cleansing and polishing actionof the brush-dentrifice combination.v The ends of such. bristles may also I be a series of ridges or other smoothly contoured I the bristles (after the balls or-coalesce'd portions are pulled off) will be produced, depending on the be melted to produce ineach individual bristle position of the bristles with relation to the' face of plate at the moment of contact. Fig. 6 shows an angular bristle end with slightlyfrounded I 'l the end is angular withoutthel; rounded edges. In Fig. 8 is. shown 'a mor'e or less rounded end, andin Figs." 9 and 10 are' showna edges. In Fig.

fiat end having cups, depressions or irregularities in the end surface. Yarious other shapes may also be produced. W 7

Our invention has many possibilities, a few of which may be mentioned .as follows:

1. To so design a plate that by a single contactwith a previously untrlmmed brush a total overall design of contour can be achieved with a single melting operation.

. 7 so shapes of the ends of. 1

irregularities if desired. p am It is very easy to break the ball -fromthe end of'the .stalk, leaving a perfectly clean fracture I which has the appearance ofhaving been glazed and is inffactmuch smoother than brushes-treated by'theabrasion method. The tooth brush to which the bristles have been aiiixed' but which have notbeen trimmed can be brought into, contact with a heated surface, the temperature of which isadjustedtomelt the bristles on contact withoutfscorching them. I I

1 By shaping the heated surface or by contacting thebrush against the heated surface in predetermined angles, the'ends of the bristles can the desired length and toproduce in the brush as I a hole the desired contour. v 1

'fter,.-this heat treatment a fair number of is, plates. scales or other forms'of accumu- {21sec melted material will remain adherent to *theI-ends of the. bristles and some of the melted material will fall away or adhere tothe heating surface-until brushed away.

The coalescediscab-like material adhering to r 2. The overall contour canbe broken down into n two ormore simple contours suchas lay-using acombination of the plates illustrated in Figs. .14

and 15. The plate shown in Fig. 14' would give a dome trim parallel to the e gth of-the'b h n to the feel, are much more regular in. contour and are much more finished in appearance than brushes finished by any method heretofore known. I vHaving described our invention, we claim:

prior or subsequent use of a plate. like in Fig; 15

would givea series of pointed tufts. when two or more plates are used to produce stepwise contouring the melted portion in each'step "can 'be 'removed before the next step or allowed to WC? against a flat plate to achieve a dome contour. 1

5. Also when desired for practical working of the invention the approximate finished contour" may be produced in the brush head by any known method such as knife or other trim, leaving each bristle slightly longer than the final length def dition.

in melting the ends of the bristles-is removed very simply after hardening by brushing for example with a stifl'wire metal brush or-co'mb or by scraping over an'angular surface which will catch under the edges of the coalesced tips and break them off.

Regardless of the method used to remove the scabrlike. material, .once removed it leaves the bristle tip ina clean and almost fire-polished con- Brushes treated in this way are much smoother l. Tliemethodof finishing the free ends of- I thermoplastic bristles for brushes, which consists the free ends of the bristles to the desired contour, there being left on the ends of the bristles after the melting enlarged, solidified portions of. therbristle material, and then pulling off the enlarged solidified portions from the bristles which leaves the ends of the bristles in a clean, polished condition.

2.The methodof forming and finishing the free ends of meltable brush bristles to the desired contour, which consists in providing a body capable of'being-heated and having a face formed with a contour like that to be imparted to the .brush bristle ends, arranging the bristles into tufts and securing them to the brush head; trimrning the bristleen'ds to approximately the desired contour, heating the contoured face of said body; to a-temperature capableof melting the 7 bristle ends, and contacting the bristle free-working ends with said heated face until the free-working ends of the bristles are melted into the contour of the heated face.

3. The method of forming and finishing the free ends of meltable brush bristles to the desired contour, which consists in providing a body capable of being heated and having a face formed with a contour like that to be imparted to the brush bristle ends, arranging the bristles into tufts and securing them to the brush head, trimming the bristle ends to approximately the desired contour, heating the contoured face of said body to a temperature capable of melting the bristle ends, and contacting the bristle ends with said heated face until the ends of the bristles are melted into the contour of the heated face, "said melting forming enlarged portions on the bristle ends, and pulling off the enlarged portions from the bristles when solidified to produce clean, polished ends on the bristles.

4. Th method of producing clean, polished ends on the ends of thermoplastic brush bristles, and forming the bristle ends collectively with a pre-determined contour on the brush face, which consists in melting the bristle ends to said contour which causes enlarged portions to solidify on the bristle ends, and pulling said solidified enlarged portions away from the bristles.

5. The method of finishing plastic filaments for brushes, which consists in contacting the ends of the filaments with a heated surface to form the contour of the filament ends in one direction of the brush, and contacting the ends of the filaments with another heated surface to form the contour of the filament ends in another direction of the brush.

6. The method of finishing plastic filaments for brushes in which the ends of the bristles have been previously trimmed to approximate contour, which consists in applying heat to the bristle ends to give them the desired final contour.

7 A brush having synthetic polymeric thermoplastic bristles the ends of which are smooth and formed with cup-like depressions to aid in bolding cleansing material applied to the brush.

8. A brush having synthetic polymeric thermoplastic bristles the ends of which are smooth and provided with depressions to retain cleansing material applied to the brush.

9. A brush of the class described comprising in combination a body member and synthetic bristles fixed at one of their ends in said body member the ends of the bristles having been formed by bringing a plurality of bristles, into contact with a heated plate of definite contour to secure the desired final contour of said plurality of bristles, the individual ends of the bristles having the desired shape and smoothness, the melted blobs caused by contact of said bristle ends with said heated plate having been removed from said ends.

GEORGE H. WANDEL. THEODORE H. RIDER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1 1,965,009 Stevens July 3, 1934 267,957 White Nov. 21, 1882 278,660 Estabrook May 29, 1883 917,811 0 Strobel Apr. 13, 1909 

